There are large variety of timers for various purposes on the market to-day. Almost invariably these timers are set for a particular time or time period in a day based on a clock setting. This invention is aimed at filling a need for a timer that may be set to activate an output switch at user desired times and to keep the switch active for user desired periods of time. There are uses such as activation of an animal feeder wherein the most desirable time or times for activation of the feeder would be times as measured by minutes or hours before and after sunrise and times before sunset and after sunset. This invention uses inputs to a microprocessor to calculate times of sunset and sunrise from latitude, longitude, time zone, and day of the month and year, and allows a user to set activation times both by clock time and by time as measured as an offset from sunrise or sunset. The microprocessor is preprogrammed to display a menu of usual settings one line at a time for all these variables and using a single pole double throw selector switch a user may select a variable to be changed and using a second single pole double throw change switch change the settings of the variables. Output times and time periods will thereafter correspond with the new settings.
For use with an animal feeder the time periods are generally chosen between 0 and 99 seconds but periods of up to 24 hours are within the purview of the invention.
With the data as outlined the programming of the microprocessor converts automatically to and from daylight saving time and corrects for leap year. Quite generally desired activation periods are on a particular day of the week and correction for leap year allows this even with unattended operation.